Since we increased the number of concurrent audit workers to two, there are going
to be instances of a single node being audited simultaneously for different segments.
If the node times out for both, we will try to write them both to the pending audits
table, and the second will return an error since the path is not the same as what
already exists. Since with concurrent workers this is expected, we will log the
occurrence rather than return an error.
Since the release default audit concurrency is 2, update testplanet default to run with
concurrent workers as well.
Change-Id: I4e657693fa3e825713a219af3835ae287bb062cb
cadb435d25